The present invention relates to a rack structure for mounting a communication apparatus which comprises a plurality of printed-board housing blocks.
Each printed-board housing block is of a box shape and houses a plurality of printed boards on which various electronic parts are attached so as to function as a communication apparatus. A plurality of such printed-board housing blocks are mounted vertically one above the other on a rack. Usually, two or three rows of such stacks of printed-board housing blocks are housed within one rack. Therefore, from the outside, the rack looks like a longitudinal box. The rack has a space which extends from the upper end thereof to the lower end thereof so that cables can be passed therethrough on the rear side of the rack. In addition to this space, a cable duct is provided adjacent to the vertical row of printed-board housing blocks within the rack so that a very large number of cables can be connected to the rack. The dimensions (width, depth, and height) of such a rack for mounting a communication apparatus are usually standardized. The front face and the side faces of each printed-board housing block (referred to as a block hereinafter) should be aligned with those of the other blocks for forming plane front and side surfaces of a rack of a standard size. The aforementioned space behind the block serves as a passage for cables and cooling air for the blocks. The depth (the distance between the front and rear end faces) of each block changes in accordance with the size of the printed boards housed therein. Also, there are special blocks which require a specified space behind them. Therefore, it is desirable to provide a rack for mounting a communication apparatus in which blocks of different depths can be mounted and in which the size of the space behind each block can be changed in accordance with the block to be mounted thereon.
As was mentioned before, when a number of cables are to be connected to the blocks, a cable duct is arranged along one of the vertical frames of the rack adjacent to the vertical stack of blocks within the rack. The cables are disposed within and along this cable duct. It is desirable that the width of the cable duct can be changeable in accordance with the number of cables and the width of the blocks.
A rack for mounting a communication apparatus according to the prior art is illustrated in FIGS. 1 to 3. FIG. 1 is a disassembled view of the rack of the prior art. FIG. 2 is a horizontal sectional view of the rack of FIG. 1, in which a block 15 and a block-mounting plate 14 are secured to frames 11 and 12. FIG. 3 is a partial horizontal sectional view of the rack of FIG. 2 illustrating means for securing the block 15 to the block-mounting plate 14.
In FIG. 1, a pair of vertical side frames 11 and 12 is illustrated. The vertical side frames 11 and 12 are interconnected at the upper end and the lower end thereof by a top frame 13 and a bottom frame 10. The top frame 13 and the bottom frame 10 are formed integrally with the vertical side frames 11 and 12. The vertical side frame 11 has an F-shaped cross section which faces the F-shaped cross section of the vertical side frame 12 and vice versa. The F-shaped vertical side frames 11 and 12 comprise side plates 11a and 12a, back plates 11b and 12b, and center plates 11c and 12c, respectively. A plurality of screw holes 11d and escape holes 11e are formed in the center plate 11c. Also, a plurality of screw holes 12d (not shown) and escape holes 12e (not shown) are formed in the center plate 12c at the same level as the screw holes 11d and the escape holes 11e of the center plate 11c. A block-mounting plate 14 comprises a rectangular main plate 14a and an upper folded rim and a lower folded rim which project frontward. Two screw holes 14c and two through holes 14b not provided with screws therein are formed in each side edge of the main plate 14a. Each through hole 14b and each screw hole 14c of the block-mounting plate 14 corresponds to the screw holes 11d and 12d and the escape holes 11e and 12e of the center plates 11c and 12c of the vertical side frames 11 and 12, respectively. As is illustrated in FIG. 2, the block-mounting plate 14 is secured to the vertical side frames 11 and 12 with screws 16 which are screwed from the front face of the block-mounting plate 14 through the through holes 14b (FIG. 1) thereof into the screw holes 11d (FIG. 1) and 12d of the center plates 11c and 12c of the vertical side frames 11 and 12, respectively. The block 15 is secured to the blcok-mounting plate 14 with screws 17 which are screwed into the screw holes 14c (FIG. 1) of the block-mounting plate 14. Connectors 15a are disposed at the upper and lower portions of the back side of the block 15. Each connector 15a is coupled to a connector 14d disposed on the block-mounting plate 14 when the block 15 is secured to the block-mounting plate 14, as is illustrated in FIG. 3. A rear cover 18 is secured to the back plates 11b and 12b of the vertical side frames 11 and 12, respectively, with an appropriate means, as is illustrated in FIG. 2. A rear space 19 is formed between the rear cover 18 and the block-mounting plate 14. This rear space 19 formed behind the blocks 15 serves as a passage for transmission cables (not shown) connected to the connectors 14d of the block-mounting plate 14 and as a cooling-air duct. The end portion 17a (FIG. 3) of each screw 17 for securing each block 15 to the block-mounting plate 14 projects from the rear face of the block-mounting plate 14 into the escape holes 12e and 11e (FIG. 1) of the center plates 12c and 11e (FIG. 1) of the vertical side frames 12 and 11 (FIG. 1), respectively.
The above-mentioned rack for mounting a communication apparatus according to the prior art has the following drawbacks:
1. It is impossible to change the depth W (FIG. 2) of the rear space in accordance with the depth of each block 15 since the block-mounting plate 14 is secured to the center plates 11c and 12c of the F-shaped vertical side frames 11 and 12, respectively.
2. The screws 17 for securing the blocks 15 to the block-mounting plate 14 and the screws 16 for securing the block-mounting plate 14 to the vertical side frames 11 and 12 interfere with each other when the height of the blocks is changed since the blocks 15 and the block mounting-plate 14 are substantially secured in common to the center pltes 11c and 12c of the vertical side frames 11 and 12, respectively.
3. Escape holes 11e and 12e must be formed in the center plates 11c and 12c of the vertical side frames 11 and 12, respectively, for receiving the end portion 17a of each screw 17 for securing the blocks 15 to the block-mounting plate 14.
Another rack structure of the prior art is disclosed in the journal "Fujitsu", vol. 30, No. 4, 1979, Page 630 (Page 72). In this rack structure, a C-shaped channel member which opens frontward is vertically disposed in the rear portion of the rack for passing cables therethrough. A plurality of blocks are vertically mounted one above the other on the C-shaped channel member.
In this structure, it is impossible to change the size of the cable passage in accordance with the depth of each block since the size of the cable passage is determined by the size of the C-shaped channel member. Therefore, the blocks to be mounted are limited to a predetermined size corresponding to the size of the C-shaped channel.
A further rack structure of the prior art is disclosed in Japanese Examined Utility Model Publication No. 56-54635. In this rack structure, a C-shaped channel member which opens backward is vertically disposed in the rear portion of the rack. A plurality of blocks are vertically mounted one above the other on the C-shaped channel member.
In this structure, it is also impossible to change the size of the cable passage formed behind the blocks in accordance with the depth of each block.
FIG. 4 illustrates a horizontal section of a rack for mounting a communication apparatus according to the prior art. The rack comprises a cable duct along the side face thereof. In FIG. 4, the left side of the drawing shows the left side of the rack, the right side of the drawing shows the right side of the rack, the lower side of the drawing shows the front side of the rack, and the upper side of the drawing shows the rear side of the rack. This is also the case in the other drawings.
As is illustrated in FIG. 4, the rack comprises a vertical left side frame 111 having an F-shaped cross section and a vertical right side frame 112. A block-mounting plate 114 is secured to the front face of a center plate 111a of the left side frame 111 and to the front face of a vertical rim 112a of the right side frame 112 with screws 116. The block-mounting plate 114 comprises a rectangular main plate 114a which is longitudinally disposed between the left and the right side frames. The upper portion of the main plate 114a is folded frontward so as to form an upper rim 114b. Similarly, the lower portion of the main plate 114a is folded frontward so as to form a lower rim 114c. Therefore, the block-mounting plate 114 has a U-shaped cross section. Connectors 114d are disposed on the front face of the main plate 114a of the block-mounting plate 114 at the upper and the lower portions thereof. Each block 115 to be mounted on the block-mounting plate 114 has connectors 115a on the upper and lower portions of the rear face thereof. Each connector 115a of each block 115 is coupled to a connector 114d of the block-mounting plate 114 when the block 115 is mounted on the block-mounting plate 114. Each block 115 is secured to the block-mounting plate 114 with screws 117. The screws 117 are screwed from the front face of the block-mounting plate 114 into screw holes (not shown) formed therein. A vertical longitudinal cover 118 is disposed in front of the right side frame 112 so as to form a cable duct 119. A rear cover 120 is disposed behind the left side frame 111 and the right side frame 112 and is secured to a back plate 111b of the left side frame 111 and to a back plate 112b of the right side frame 112 with an appropriate means. A rear space 121 is formed between the rear cover 120 and the block-mounting plate 114. This rear space 121 is used for disposing cables (not shown) for connecting blocks to each other within the rack via the connectors 114d and 115a. The rear space 121 is also used as a passage for cooling air. The cable duct 119 is used as a passage for cables (not shown) introduced from outside the rack, for connecting the blocks within the rack with other communication apparatuses or other devices disposed outside the rack.
In the above-mentioned rack structure, the width l.sub.2 of the cable duct 119 is limited to a predetermined value depending upon the width l.sub.1 of the right side frame 112. Therefore, the width l.sub.3 of the space for mounting the blocks 115 is limited to a value corresponding to the width of the cable duct 119. In order to change the widths l.sub.2 and l.sub.3, it is necessary to prepare another right side frame of a different width l.sub.1. However, the preparation of a right side frame of a desired size is troublesome and increases the cost of the rack structure. Also, the space within the rack is not effectively used for mounting blocks and disposing cables in accordance with the size and number of blocks to be mounted.